Short-wave radiotherapy system



J. L. HATHAwAY SHORT-WAVE RADIOTHERAPY SYSTEM y Filed July 25, 1936 2 Sheets-Sheet l lNvENToR .1.- L. HATHAWAY BY ATTRNEY Dec.`3, 1940. J. L, HATHAWAY 2,223,447

SHORT-WAVE RADIOTHERAPY SYSTEM 2 sheets-Sheet 2 Filed July 23, 1936 INVENTOR J. L, HATHAWAY ATTORN EY Patented Dec. 3, 1940 UNITED STATES SHORT-WAVE RADIOTHERAPY SYSTEM Jarrett L. Hathaway, Manhasset, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application July 23, 1936, Serial No. 92,101

6 Claims.

This .invention relates to a system of diathermy or short-wave radiotherapy.

On object of this invention is to improve the' present system and apparatus for curing certain diseases by the use of short wave radiotherapy apparatus.

Another object of this invention is to reduce the risks which are ever-present to the patient while being treated. ,f

A further object of this4 invention is/to provide a means whereby undesired radio frequency radiation may be minimized.

Av feature of this invention is the relatively low voltage required in the lines connecting the radio frequency generating apparatus to the appli caters.

The present system of radiotherapy in its or` dinary routine use is subject to several objectionable defects, such as the burn hazards to the patients skin, and also various insulation difficulties are freqently encountered. Also, the longcable'generally employed gives use to undesired radio frequency radiation.

Briefly, this invention comprises a radiotherapy machine as is Well known in the medical science, the machine being altered in such a manner that the output portion or the high frequency resonating system is divided into two parts, so that the cable connecting from the machine to the applicat'or or applicators is maintained at a low voltage by means of a low-loss cable or cables, the other portion of the resonant circuit being completed at the applicator or applicators, by providing lumped inductance for magnification of the voltage at the applicator or'applicators.

This invention will be best be understood by referring to the .accompanying drawings, in

Whichz` Fig. 1 is a circuit diagram of this invention;

Fig. 2 is a sectional detail ,ofan improved -applicator; l

Fig. 3 is a front elevation of Fig. 2;

Fig. 4 is "a sectional detail of an improved small applicator; while Fig. 5 is a sectional detail of a modification of Fig. 4.

Referring no w in detail to the drawings, I indicates an alternating current source'whichv is connected atterminals 2 and 3 to the diathermy machine 4 which contains the high frequency apparatus, such as oscillator tube 5, primary inductance 6 and resonant tuning condenser 1. An output coil 8 is grounded at the center point 9 and its ends are connected to output terminals I0 ments, such as dental or other oral amictions.

and II. The inductance and the capacitive values of members 6, 1 and 8 are so chosen that the output voltage at the terminals I6 and Il is substantially reduced below the voltage across 6.

In order to keep the radiation energylosses at 5 a minimum, terminals I0 and II are connected through a low capacity cable I2 to the applicators\ I3 and I4. Applicators I3 and I4 are each identical in structure and are shown in detail by Figs. 2 and3' in which an outer pear-shaped-cas- 1 0 ing I5 which is made of any suitable vinsulating material, such as hard rubber or any phenol condensation product, for example Bakelite, contains the resonating portion of the radio frequency circuit, including a condenser plate or 1, electrode .I6 and inductance I1. The condenser plate or electrode I6 is secured in the flange-like portion 26 inthe front of casing I5 and is retained in place by a groove in said casing. 'The condenser plate is covered in front by a thin insulator I9. Inductance I1 may be supported by a stud-like metallic member 20 which is fastened tocondenser plate I6 in any suitable manner, such as by riveting at point 2I.. The other` end of inductance--coil I1 is secured by an insulating stud 22 which is fastened to the end portion of casing I5 at point 23. The inductance I1 and condenser electrode I6 are connected to the` machine 4 by a lead or conductor 24 which is secured withiny the high frequency cable I2, `ca o ble I2 being securely fastened to a point 25 on casing I5. Flange 26 on the casing'l serves to space the condenser plate 4I6 from the patients body and is provided with slots I5q, and means for holding the applicator to the patient, such as by the use lof straps 21 passing through slots I5a. Fig. 4 -shows a single electrode system utilizing a small cylindical electrode which is especially suitable for .treatment of highly localized ailo The small electrodel system comprises a cylinder 30 of insulating material having a bushing' 3| also of insulating material for mechanically supporting an inner centrally located applicator tube s 32 whichis of low loss insulating material and serves the dual function of a. handle and a winding form for the coil 33. One end of coil 33 is connected to an output lead I2, theother end terminating at the metallic electrode 34. As one 5 0 of the .ends of tube 3U is open, a mica safety disc 35 is provided to protect the patient from coming in direct contact with metallic electrode 34.

Fig.` 5 illustrates another embodiment which isv a modification of Fig. 4 which is simple in its 65 Ainsulation losses.

of a low capacity flexible cable for connection general construction; It comprises a glass tube 36 open at one end and closed at the other. The

open end is closed by an insulation member 3'I of high grade rubber having an aperture 38 for supporting a heavy self-supporting coil 39 which is terminated with a curved or'semi-spherical electrode 40.

The operation of this improved system is similar to that of any well-known diathermy machine, except that the magnification of the voltage is maintained chiefly at thev extreme end of the applicator, instead of in the machine itself.

.The applicators serve to resonate the output circuit and the voltage is built up in them rather than in the machine so that the connecting cable or cables' may be held at a relatively low potential thus protecting both the patient and the physician operating the same, as well as reducing This makes possible the use from machine to the electrodes. Undesired radio frequency radiation which causes disturbances in local radio receivers is also substantially reduced.

While only afew modiiications are shown, it is distinctly understood that the construction is capable of taking other forms and should not be limited to the forms shown, except by such limitations as are clearly imposed in the appended claims.

What is claimed is: 1. A short wave radiotherapy system comprising a source of radio frequency power the output source -of which comprises a pair of terminals maintained at a low potential point, an applicator comprising a bell-shaped insulating casing, having a flanged end with means to fasten said applicator to a portion of the human body, a lumped inductance within said casing, a support member for said lumped inductance located at one end of said insulating casing, and a condenser electrode connected in series with said lumped'inductance and located within said casing at an end opposite said, support member.

.2. A short wave radiotherapy system comprising a source of radio frequency power the output source of which comprises a pair of terminals vmaintained at a low potential point, an applicator comprising a bell-shaped insulating casing having 4a anged and, a condenser plate mounted near said flanged end, and means for fastening. spacing and insulating said condenser plate from a portion of the human body, an inductance connected in series with said condenser `plate and supported at an end opposite said condenser plate within said insulating casing.

3. A short wave radiotherapy system comprislng a source of radio frequency power the output source of which comprises a pair of terminals maintained at a 'low potential point, applicators respectively connected to the respective ones of ,the output terminals of said source of radio frequency power which is maintained at a low potential point, each one of said applicators comprising an insulating casing, an inductance coil within said casing, a condenser plate located at one end of saidA casing and supported thereby said inductance coil and said condenser plate being connected in series so as to form a resonant circuit, and an insulating cover surrounding the front portion of said condenserl electrode.

4. A short wave radiotherapy system comprising a source of radio. frequency power the output source of which comprises a pair of terminals maintainedv at a low potential point, applicatorrespectively connected to the respective ones of the output terminals of said source of radio frequency power which is maintained at alow potential point, each one of said applicators comprising an insulating casing, an inductance coil within said casing, a condenser plate located at one end 4of .said casing and' supported thereby,

said inductance coil and said condenser plate be-A ing connected in series so as to form a resonant circuit, an insulating cover surrounding the front portion of said condenser plate, and an insulating spacing rim portion extending beyond said condenser plate. 4

' 5. A. short wave radiotherapy system comprising a source of\ radio frequency power the output source of which comprises a pair of terminalspmaintainediat a vlow potential point, applicators respectively connected to the respective ones of the outputterminals of said source of radio frequency power which is maintained at a low potential point, each one of said applicators comprising an insulating casing, an inductance coil within said casing, a condenser plate located at one end of said casing and supported thereby said inductance coil and said condenser plate being connected in series so as to form a resonant anged end, and means for -fastening, spacing and insulating said condenser plate from a portion ofthe human body, a pair of retaining members located in said slots; an inductance connected in series with said condenser plate and supported at an end opposite said condenser plate Within said insulating casing.

-JARRE'IT i.; HA'rHAwAv. 

